Angioplasty (percutaneous transluminal angioplasty (PTA) or percutaneous transluminal coronary angioplasty (PTCA) is a procedure that is used to dilate occluded vessels in the vascular system. The procedure typically consists of multiple steps. First, an introducer sheath is placed in the patient to provide a point of access for catheter placement. Once access has been obtained, sometimes a guiding catheter is placed in to the vessel near the occlusion and injected with an x-ray sensitive dye (contrast) that is to be infused into the blood stream. The contrast can also be injected through the introducer sheath depending on the location of the occlusion relative to the introducer sheath. The farther the distance the more likely a guiding catheter will be used to facilitate localizing the contrast for improved image quality and to minimize the amount of contrast for patient safety.
The contrast is viewed under a fluoroscope as it travels through the blood stream to identify the block or constricted vessel. After the location of the blockage is identified, the guiding catheter is extracted and replaced with an angioplasty balloon catheter used to dilate the vessel. The standard angioplasty balloon catheter is constructed with a high-pressure, non-compliant balloon on the distal tip and a means for inflating the balloon on the proximal end. This catheter is inserted into the introducer sheath and guided into position by radiopaque marker bands on the catheter shaft. Once the catheter is appropriately placed at the point of the blockage, the balloon is inflated at high pressure using an inflation syringe (insufflator) to dilate the vessel. After dilation the catheter is extracted and the guiding catheter is once again placed into the vessel to inject the contrast to confirm the blockage has been fully opened.
Inflation syringes are available, for example, Taut® System One, Teleflex Medical, Research Triangle Park, N.C.; Medflator®, Smiths Medical, St. Paul, Minn.; Basix Compak®, Merit Medical, South Jordan, Utah. Insufflation devices for inflating angioplasty balloons have been described (see, e.g., Miley et al (2011) Neurosurgery. 69:ons161-ons168). Inflation syringe or insufflator may be configured to deliver pressure in the range of 0-25 atmospheres. Processes for delivering inflation media, diagnostic agents, therapeutic agents to a vascular lumen (or other lumen in the body) or to a balloon, by way of syringe and catheter, are disclosed by U.S. Pat. No. 8,043,313 of Krolik et al, and of U.S. Pat. No. 8,298,252 of Krolik et al, where are each incorporated by reference in their entirety. Therapeutic agent can include agent to reduce re-stenosis, such as anti-proliferative drug (see, e.g., U.S. Ser. No. 13/644,022 of Krolik, which is incorporated herein in its entirety).
Some physicians prefer to measure the intravascular pressure before and after the dilatation of the vessel. This measurement can be achieved by using disposable pressure transducers connected to the balloon catheter's inner lumen, which is exposed to the bloodstream. This technique allows for a more precise method of measuring the performance of the angioplasty procedure.